diff --git a/src/monger/joda_time.clj b/src/monger/joda_time.clj
index 7f0749f..fbd799d 100644
--- a/src/monger/joda_time.clj
+++ b/src/monger/joda_time.clj
@@ -1,5 +1,6 @@
 (ns monger.joda-time
-  (:import (org.joda.time DateTime DateTimeZone))
+  (:import [org.joda.time DateTime DateTimeZone ReadableInstant]
+           [org.joda.time.format ISODateTimeFormat])
   (:use [monger.conversion])
   (:require [clojure.data.json :as json]))
 
@@ -9,7 +10,7 @@
 
 (extend-protocol ConvertToDBObject
   org.joda.time.DateTime
-  (to-db-object [^org.joda.time.DateTime input]
+  (to-db-object [^DateTime input]
     (to-db-object (.toDate input))))
 
 (extend-protocol ConvertFromDBObject
@@ -20,7 +21,5 @@
 
 (extend-protocol json/Write-JSON
   org.joda.time.DateTime
-  (write-json [^org.joda.time.DateTime object out escape-unicode?]
-    ;; TODO: use .printTo(Writer) here instead of ignoring
-    ;;       out parameter. MK.
-    (.print (org.joda.time.format.ISODateTimeFormat/dateTime) object)))
+  (write-json [^DateTime object out escape-unicode?]
+    (json/write-json (.print (ISODateTimeFormat/dateTime) ^ReadableInstant object) out escape-unicode?)))
diff --git a/test/monger/test/lib_integration.clj b/test/monger/test/lib_integration.clj
new file mode 100644
index 0000000..1d82401
--- /dev/null
+++ b/test/monger/test/lib_integration.clj
@@ -0,0 +1,27 @@
+(ns monger.test.lib-integration
+  (:use [clojure.test]
+        [monger.json]
+        [monger.joda-time]
+        [monger.conversion])
+  (:import [org.joda.time ReadableInstant]
+           [org.joda.time.format ISODateTimeFormat]
+           [java.io StringWriter PrintWriter])
+  (:require [clojure.data.json :as json]
+            [clj-time.core     :as t]))
+
+
+(deftest serialization-of-joda-datetime-to-json
+  (is (= "\"2011-10-13T23:55:00.000Z\"" (json/json-str (t/date-time 2011 10 13 23 55 0)))))
+
+
+(deftest conversion-of-joda-datetime-to-db-object
+  (let [d (to-db-object (t/date-time 2011 10 13 23 55 0))]
+    (is (instance? java.util.Date d))
+    (is (= 1318550100000 (.getTime ^java.util.Date d)))))
+
+
+(deftest conversion-of-java-util-date-to-joda-datetime
+  (let [input  (.toDate (t/date-time 2011 10 13 23 55 0))
+        output (from-db-object input false)]
+    (is (instance? org.joda.time.DateTime output))
+    (is (= input (.toDate output)))))